Fluorescent elastic yarn and method for producing the same

ABSTRACT

Disclosed is a fluorescent elastic yarn and method for producing the same. The fluorescent elastic yarn can fluoresce sufficiently to allow a thin elastic yarn to be seen by the naked eye when ultraviolet light is irradiated to the fluorescent elastic yarn by adding a novel organic additive to a polymer or a spinfinish. Therefore, the fluorescent elastic yarn of the present invention is advantageous in that production of inferior covered yarns is prevented.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates, in general, to a fluorescentelastic yarn and a method for producing the same and in particular, to afluorescent elastic yarn which can fluoresce sufficiently to allow athin elastic yarn to be seen by the naked eye when ultraviolet light isirradiated to the fluorescent elastic yarn by adding a novel organicadditive to a polymer or a spinfinish, and a method of producing thesame.

[0003] 2. Description of the Prior Art

[0004] An elastic yarn has been applied to various fields, and a processof knitting and weaving the elastic yarn covered with a natural fiberhas been widely used in the art. Various types of elastic yarns, forexample, a core spun yarn in which cotton or a rayon fiber is covered onthe elastic yarn, and a covered yarn in which a synthetic fiber such asnylon and polyester is covered on the elastic yarn, are used to produceelastic textile fabrics or knitted goods requiring elasticity.

[0005] However, there is a problem during a covering process of theelastic yarn in that a breakage of the elastic yarn cannot be discoveredin good time, and so inferior products having only the covered yarnwound without the elastic yarn may be produced. This problem causes areduction in productivity of the covered elastic yarn and a waste of thecovered yarns. Accordingly, there remains a need for the development ofa novel method capable of finding a breakage of the elastic yarn in goodtime.

[0006] A conventional method of finding a breakage of the elastic yarnis based on a principle that titanium-based or magnesium-based inorganicadditives added into the elastic yarn emit a dark violet ray whenirradiated by ultraviolet light. However, the inorganic additives arenot only added into the elastic yarn in order to avoid the aboveproblem, but also added into the elastic yarn so as to improve dullingeffect and anti-blocking property, and so the problem cannot be overcamebasically. Furthermore, the conventional method is disadvantageous inthat when thickness of the elastic yarn is less than 40 deniers, or asmall capacity device such as a portable UV radiator is used todiscriminate breaking of the elastic yarn in a work place, it is almostimpossible to find the breakage.

SUMMARY OF THE INVENTION

[0007] Therefore, it is a feature of the present invention to provide afluorescent elastic yarn which can be discriminated by fluorescence whenultraviolet light is irradiated to it.

[0008] It is another feature of the present invention to provide amethod for producing the fluorescent elastic yarn.

[0009] It is the other feature of the present invention to provide afluorescent elastic yarn covered with hard fiber.

[0010] In accordance with an aspect of the present invention, there isprovided a fluorescent elastic yarn comprising 0.001 to 20 wt % of afluorescent brightener.

[0011] In accordance with another aspect of the present invention, thereis provided a method for producing a fluorescent elastic yarn comprisingthe step of spinning a polyurethane-urea copolymer, wherein afluorescent brightener is mixed with the polyurethane-urea copolymer inan amount of 0.001 to 20 wt %.

[0012] In accordance with another aspect of the present invention, thereis provided a method for producing a fluorescent elastic yarn comprisingthe step of spinning a polyurethane-urea copolymer, wherein a spinfinishhaving a fluorescent brightener dispersed therein is applied to a spunelastic yarn in such an amount that a content of the fluorescentbrightener in the resulting elastic yarn ranges from 0.001 to 20 wt %.

[0013] In accordance with the other aspect of the present invention,there is provided a method for producing a covered fluorescent elasticyarn, comprising the step of covering a core yarn, wherein the core yarnis the fluorescent elastic yarn.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0014] A segmented polyurethane-urea copolymer useful for production ofa fluorescent elastic yarn of the present invention is produced byreacting organic diisocyanate with polydiol to produce a prepolymer, andthen dissolving the prepolymer in an organic solvent and reacting withdiamine and monoamine.

[0015] The organic diisocyanate used to produce the segmentedpolyurethane-urea copolymer includes, not limited to,diphenylmethane-4,4′-diisocyanate, hexamethylenediisocyanate,toluenediisocyanate, butylenediisocyanate, and hydrogenatedP,P-methylenediisocyanate.

[0016] The polydiol used to produce the segmented polyurethane-ureacopolymer includes, not limited to, polytetramethylene ether glycol,polypropylene glycol, and polycarbonate diol.

[0017] Furthermore, a diamine such as ethylene diamine, propylenediamine, and hydrazine can used as a chain extender, and a monoaminesuch as diethylamine, monoethanol amine, and dimethyl amine can be usedas a chain termination agent.

[0018] Useful for covering the elastic yarn according to the presentinvention may be cotton, rayon, nylon, polyester, or cellulose.

[0019] A fluorescent brightener characteristically added to an elasticyarn in the present invention may be mixed with a polymer used as a rawmaterial of the elastic yarn before the elastic yarn is spun.Alternatively, the fluorescent brightener may be added into a spinfinishwhich is applied to a spun elastic yarn after spinning of the elasticyarn. The fluorescent brightener is added to the elastic yarn in such anamount that a fluorescent brightener content ranges from 0.001 to 20 wt% in the resulting elastic yarn.

[0020] When the fluorescent brightener content is less than 0.001 wt %,a fluorescent effect is poor. On the other hand, when the content ismore than 20 wt %, dispersability of the fluorescent brightener in apolymer or spinfinish is poor and so the fluorescence of the fluorescentelastic yarn is non-uniform though the fluorescence is absolutelybright, and the fluorescent elastic yarn cannot be produced economicallydue to the heavy cost of brightener.

[0021] The fluorescent brightener used in the present invention include,not limited to, a stilbene-based fluorescent brightener, apyrazolone-based fluorescent brightener, an imidazole-based fluorescentbrightener, an oxazole-based fluorescent brightener, a coumarin-basedfluorescent brightener, a rhodamine-based fluorescent brightener, and afluorescein-based fluorescent brightener. Specific examples of eachfluorescent brightener are as follows:

[0022] Stilbene-based fluorescent brightener: C.I.(Color Index)Fluorescent Brighteners No. 24, 77, 84, 85, 90, 97, 132, 151, 153, 154,and 166, which are kinds of ((Bis)triazinylaminostilbene)) orderivatives thereof;

[0023] Pyrazolone-based fluorescent brightener: C.I. FluorescentBrighteners No. 54 and 124;

[0024] Imidazole-based fluorescent brightener: C.I. FluorescentBrighteners No. 45, 133, 140, 150, 189, 228, and 2-isopropylimidazole(CAS(Chemical Abstract Society)# 36947-68-9);

[0025] Oxazole-based fluorescent brightener: C.I. FluorescentBrighteners No. 170, 171, 219, 258, 259, and(2,2′-2,5-diophenydil)bis[5-(1,1-dimethylethyl)]-benzoxazol (usuallyreferred to as ‘uvitex OB’);

[0026] Coumarin-based fluorescent brightener: C.I. FluorescentBrighteners No. 52, 69, 78, 91, 130, 152, 156, 162, Coumarin 1(CAS#91-44-1, 7-diethylamino-4-methyl coumarin), and Coumarin 6(CAS#38215-36-0, 3-(2-benzotiazolyl)-7-diethylamino coumarin);

[0027] Rhodamine-based fluorescent brightener: Rhodamine B (CAS#81-88-9,N-[9-(2-carboxyphenyl)-6-diethylamino-3H-xanthen-3-ylidene]-N-ethylethanammoniumchloride), and Rhodamine isocyanate (CAS# 36877-69-7); and

[0028] Fluorescein-based fluorescent brightener: Fluorescein (CAS#2321-07-5), and Fluorescein isothiocyanate (CAS# 3326-32-7).

[0029] It is preferable that the fluorescent brightener is dispersed inan organic solvent prior to being mixed with a polymer or spinfinish.The organic solvent includes, not limited to, methanol and hexyleneglycol (CAS# 107-41-5, 2-methyl-2,4-pentandiol).

[0030] According to the present invention, additives such as a UVstabilizer, an antioxidant, a NO_(x) gas yellowing resistance agent, ananti-blocking agent, a dye fastness improver, a chlorine-resistingagent, and a dulling agent may be added to the elastic yarn during dryspinning of the elastic yarn.

[0031] When the fluorescent brightener is added to a dissolved polymerbefore spinning of the elastic yarn, the fluorescent brightener displaysan eternal fluorescent effect under ultraviolet light, and so thefluorescent elastic yarn can be applied to clothes for a special userecognized by a UV radiator. Alternatively, when the fluorescent elasticyarn is produced using the spinfinish containing the fluorescentbrightener, the fluorescent elastic yarn is advantageous in that thefluorescent elastic yarn is readily visually inspected because thefluorescent brightener is coated on the surface of the elastic yarn.Also, the knitted or woven fabric applied with the fluorescent elasticyarn mentioned above can be used for various purpose according to user'srequirements, because the fluorescent brightener can be detached fromthe elastic yarn very easily under scoring and post processing of thefabric.

[0032] A better understanding of the present invention may be obtainedby reading the following examples which are set forth to illustrate, butare not to be construed to limit the present invention.

EXAMPLE 1

[0033] 518 g of diphenylmethane-4,4′-diisocyanate was reacted with 2328g of polytetramethylene ether glycol (molecular weight: 1800) under anitrogen gas atmosphere at 85° C. for 90 min to produce a prepolymercontaining isocyanate groups positioned at both terminations thereof.The prepolymer thus produced was cooled to room temperature, and 4643 gof dimethylacetamide was added to the cooled prepolymer to produce aprepolymer solution.

[0034] After that, a solution, in which 54 g of propylene diamine and9.1 g of diethylamine were dissolved in 1889 g of dimethylacetamide, wasadded to the prepolymer solution at 10° C. or less to produce a segmentpolyurethane-urea copolymer solution.

[0035] Additives such as a UV stabilizer, an antioxidant, a yellowingresistance agent, a dye fastness improver, a magnesium-basedanti-blocking agent, and a titanium-based dulling agent were added tothe above segmented polyurethane-urea copolymer solution, and Coumarin 1(CAS# 91-44-1, 7-diethyl amino-4-methylcoumarin) dispersed in hexyleneglycol (CAS# 107-41-5, 2-methyl-2,4-pentanediol) in a weight ratio of2:8 was added to the polymer solution in such an amount that a Coumarin1 content was 5 wt % based on the resulting polymer solid. The resultingpolymer was subjected to a defoaming process, drawn at a spinningtemperature of 250° C. by a dry spinning process, and wound to produce apolyurethane-urea elastic yarn with a thickness of 10 deniers. Theelastic yarn was covered with a polyester false twist yarn with athickness of 75 deniers with the use of conventional covering machines.Physical properties of the elastic yarn and the covered elastic yarnwere evaluated, and results are described in Table 1.

EXAMPLES 2 TO 4

[0036] The procedure of example 1 was repeated except that the resultingelastic yarns were 20, 40, and 140 deniers in thickness. Physicalproperties of the resulting elastic yarns are described in Table 1.

EXAMPLE 5

[0037] 518 g of diphenylmethane-4,4′-diisocyanate was reacted with 2328g of polytetramethylenether glycol (molecular weight: 1800) under anitrogen gas atmosphere at 85° C. for 90 min to produce a prepolymercontaining isocyanate groups positioned at both terminations thereof.The prepolymer thus produced was cooled to room temperature, and 4643 gof dimethylacetamide was added to the cooled prepolymer to produce aprepolymer solution.

[0038] After that, a solution, in which 54 g of propylene diamine and9.1 g of diethylamine were dissolved in 1889 g of dimethylacetamide, wasadded to the prepolymer solution at 10° C. or less to produce asegmented polyurethane-urea copolymer solution.

[0039] Additives such as a UV stabilizer, an antioxidant, a yellowingresistance agent, a dye fastness improver, a magnesium-basedanti-blocking agent, and a titanium-based dulling agent were added tothe above segmented polyurethane-urea copolymer solution, and theresulting polyurethane-urea copolymer solution was subjected to adefoaming process and drawn at a spinning temperature of 250° C. by adry spinning process. Coumarin 1 (CAS# 91-44-1, 7-diethylamino-4-methylcoumarin) was dispersed in hexylene glycol (CAS# 107-41-5,2-methyl-2,4-pentanediol) in a weight ratio of 2:8 to produce adispersion liquid, and the dispersion liquid was added to the resultingpolyurethane-urea copolymer polymer solution in such an amount that thedispersion liquid is 10 wt % based on a spinfinish generally used inwinding the elastic yarn, for example, comprising polydimethylsiloxaneand pure. 5 wt % spinfinish based on the elastic yarn was applied to asurface of the elastic yarn to produce the resulting elastic yarn with athickness of 10 deniers. The fluorescent brightener content in theresulting elastic yarn was 0.1 wt %. The resulting elastic yarn wascovered with a polyester false twist yarn with a thickness of 75 denierswith the use of conventional covering machines. Physical properties ofthe elastic yarn and the covered elastic yarn were evaluated, andresults are described in Table 1.

EXAMPLES 6 TO 8

[0040] The procedure of example 5 was repeated except that the resultingelastic yarns were 20, 40, and 140 deniers in thickness. Physicalproperties of the resulting elastic yarns and covered elastic yarns wereevaluated, and results are described in Table 1.

COMPARATIVE EXAMPLES 1 TO 4

[0041] The procedure of example 1 was repeated to produce the resultingelastic yarns of 10, 20, 40, and 140 deniers except that a fluorescentdispersion liquid was not applied to the elastic yarn. Physicalproperties of the resulting elastic yarns and covered elastic yarns wereevaluated, and results are described in Table 1.

EXAMPLES 9 TO 10

[0042] The procedure of example 3 was repeated except that each Coumarin1 added to a polymer solution was 0.001 and 20 wt % based on theresulting polymer solid.

COMPARATIVE EXAMPLES 5 TO 6

[0043] The procedure of example 3 was repeated except that each Coumarin1 added to a polymer solution was 0.0001 and 25 wt % based on theresulting polymer solid.

EXAMPLE 11

[0044] The procedure of example 7 was repeated except that 0.1 wt %dispersion liquid having a fluorescent brightener dispersed thereinbased on a spinfinish was added to an elastic yarn, 5 wt % spinfinishbased on the elastic yarn was applied to a surface of the elastic yarnand the resulting mixture was wound to produce the resulting elasticyarn with a thickness of 40 deniers, and a fluorescent brightenercontent in the resulting elastic yarn was 0.001 wt %.

COMPARATIVE EXAMPLE 7

[0045] The procedure of example 7 was repeated except that 0.01 wt %dispersion liquid having a fluorescent brightener dispersed thereinbased on a spinfinish was added to an elastic yarn, 5 wt % spinfinishbased on the elastic yarn was attached to a surface of the elastic yarnand the resulting mixture was wound to produce the resulting elasticyarn with a thickness of 40 deniers, and a fluorescent brightenercontent in the resulting elastic yarn was 0.0001 wt %. TABLE 1Luminosity under UV (25 lux) Measurement by Visual Visual Luxmeter (lux)inspection inspection (whole elastic (a string of (a string of Deniers(d) yarn package) elastic yarn) covered yarn) Whiteness Ex. 1 10 4˜6Possible Possible ⊚ (fluorescent light) Ex. 2 20 4˜6 Possible Possible ⊚(fluorescent light) Ex. 3 40 4˜6 Possible Possible ⊚ (fluorescent light)Ex. 4 140 4˜6 Possible Possible ⊚ (fluorescent light) Ex. 5 10 8˜10Possible Possible ⊚ (fluorescent light) Ex. 6 20 8˜10 Possible Possible⊚ (fluorescent light) Ex. 7 40 8˜10 Possible Possible ⊚ (fluorescentlight) Ex. 8 140 8˜40 Possible Possible ⊚ (fluorescent light) Ex. 9 401˜2 Possible Possible ◯ (fluorescent light) Ex. 10 40 35˜40 PossiblePossible ⊚ (fluorescent light) Ex. 11 40 1˜2 Possible Possible ◯(fluorescent light) Co. Ex. 1 10 0˜1 Impossible Impossible Δ (darkviolet) Co. Ex. 2 20 0˜1 Impossible Impossible Δ (dark violet) Co. Ex. 340 0˜1 Impossible Impossible Δ (dark violet) Co. Ex. 4 140 0˜1 PossiblePossible Δ (dark violet) Co. Ex. 5 40 0˜1 Impossible Impossible Δ(fluorescent light) Co. Ex. 6 40 40˜45 Possible Possible ⊚ (fluorescentlight) Co. Ex. 7 40 0˜1 Impossible Impossible Δ (fluorescent light)

[0046] From the results of Table 1, it can be seen that a thin elasticyarn of 40 d or less without the fluorescent brightener is difficult tobe visually inspected under UV, and when a fluorescent brightenercontent based on the resulting polymer is 20 wt % or more as in the caseof example 6, the elastic yarn has an excellent fluorescent effect, buthas disadvantages of poor unwinding property of and poor dispersibilityof a fluorescent substrate.

EXAMPLES 12 TO 18

[0047] The procedure of example 7 was repeated except that a fluorescentbrightener and a dispersing agent are different from each other as shownin Table 2. Physical properties of the resulting elastic yarns andcovered elastic yarns were evaluated, and results are described in Table2. TABLE 2 C.I. # or Luminosity Fluorescent commercial Dispersing under25 lux White- Ex. brightener name agent UV (lux) ness 12 Stilbene 24Methanol 2˜4 ◯ (blue violet) 77 Hexylene 5˜6 ⊚ glycol 84 Methanol 5˜6 ⊚(blue violet) ⊚ 85 Methanol 4˜6 ⊚ (blue violet) 90 Methanol 5˜6 ⊚ (blueviolet) 97 Hexylene 5˜6 (blue) ⊚ glycol 132 Hexylene 5˜6 (blue) ⊚ glycol151 Methanol 2˜4 ◯ (red blue) 153 Methanol 2˜4 (blue) ◯ 154 Methanol 5˜6(blue) ⊚ 166 Methanol 5˜6 ⊚ (green blue) 13 Pyrazolone 54 Methanol 2˜3 ◯(green blue) 124 Methanol 2˜3 (blue) ◯ 45 Methanol 4˜6 (blue) ⊚ 133Methanol 4˜6 (blue) ⊚ 140 Methanol 4˜6 (blue) ⊚ 150 Methanol 5˜7 (blue)⊚ 14 Imidazole 189 Methanol 4˜6 (blue) ⊚ 228 Hexylene 4˜6 (blue) ⊚glycol 2-isopropyl Hexylene 4˜6 (blue) ⊚ imidazole glycol 170 Methanol2˜4 (blue) ◯ 171 Methanol 2˜4 (blue) ◯ 219 Acetone 1˜2 Δ (red blue) 15Oxazole 258 Acetone 1˜2 Δ (blue violet) 259 Methanol 2˜4 (blue) ◯ 16Coumarin 52 Methanol 3˜6 ⊚ (blue violet) 69 Acetone 3˜6 ⊚ (blue violet)78 Acetone 3˜6 ⊚ (blue violet) 91 Acetone 3˜6 ⊚ (blue violet) 130Hexylene 3˜6 (violet) ⊚ glycol 152 Acetone 3˜6 ⊚ (green blue) 156Acetone 3˜6 (blue) ⊚ 162 Acetone 3˜6 (blue) ⊚ Coumarin 1 Hexylene  8˜10⊚ glycol Coumarin 6 Hexylene  8˜10 ⊚ glycol 17 Rhodamine Rhodamine BAcetone 6˜8 (blue) ⊚ Rhodamine Acetone 6˜8 (blue) ⊚ isocyanate 18Fluorescein Fluorescein Acetone 5˜7 (green) ⊚ Fluorescein Acetone 5˜7(green) ⊚ isocyanate

[0048] As described above, the present invention is advantageous in thata fluorescent elastic yarn of this invention can be visually inspectedunder UV even though the elastic yarn is covered with a polyester falsetwist yarn, and so it can be discriminated whether a thin elastic yarnof 10 deniers is present or not, thereby production of inferior coveredyarn (No presence of elastic yarn) is minimized and productivity of thefluorescent elastic yarn is improved in a downstream process ofproducing the fluorescent elastic yarn.

[0049] The present invention has been described in an illustrativemanner, and it is to be understood that the terminology used is intendedto be in the nature of description rather than of limitation. Manymodifications and variations of the present invention are possible inlight of the above teachings. Therefore, it is to be understood thatwithin the scope of the appended claims, the invention may be practicedotherwise than as specifically described.

What is claimed is:
 1. A fluorescent elastic yarn comprising 0.001 to 20wt % of a fluorescent brightener.
 2. A method for producing afluorescent elastic yarn comprising the step of spinning apolyurethane-urea copolymer, wherein a fluorescent brightener is mixedwith the polyurethane-urea copolymer in an amount of 0.001 to 20 wt %.3. A method for producing a fluorescent elastic yarn comprising the stepof spinning a polyurethane-urea copolymer, wherein a spinfinish having afluorescent brightener dispersed therein is applied to a spun elasticyarn in such an amount that a content of the fluorescent brightener inthe resulting elastic yarn ranges from 0.001 to 20 wt %.
 4. The methodaccording to claim 2, wherein the fluorescent brightener is selectedfrom the group consisting of a stilbene-based fluorescent brightener, apyrazolone-based fluorescent brightener, an imidazole-based fluorescentbrightener, an oxazole-based fluorescent brightener, a coumarin-basedfluorescent brightener, a rhodamine-based fluorescent brightener and afluorescein-based fluorescent brightener.
 5. The method according toclaim 3, wherein the fluorescent brightener is selected from the groupconsisting of a stilbene-based fluorescent brightener, apyrazolone-based fluorescent brightener, an imidazole-based fluorescentbrightener, an oxazole-based fluorescent brightener, a coumarin-basedfluorescent brightener, a rhodamine-based fluorescent brightener and afluorescein-based fluorescent brightener.
 6. A method for producing acovered fluorescent elastic yarn, comprising the step of covering a coreyarn, wherein the core yarn is the fluorescent elastic yarn according toclaim
 1. 7. The method according to claim 6, wherein the fluorescentelastic yarn is covered with at least one selected from the groupconsisting of cotton, rayon, nylon, polyester and cellulose.
 8. Acovered fluorescent elastic yarn produced through the method accordingto claims 6 and
 7. 9. A core spun yarn produced through the methodaccording to claim 5.